Insulating material



Sept. 19, 1939. K. E. PRINDLE 2,173,726

INSULAT ING MATERIAL Filed Jan. 5, 1958 Y INVENTOR.

BY M/ ATTORNEY.

UNITED STATES PATENT OFFICE INBULATING MATERIAL Karl E. Prindle,

to The Dobeckm a corporation of Ohio .Shaker Heights, Ohio,

alaignor Cleveland, Ohio,

Application January 5. 1938, Serial No. 183,410

6Claims.

This invention relates to the art of insulating electrical equipment.More particularly, this invention relates to an electrical motor andspecifically to insulating the windings from the arma- 5 ture core andthe stator coils (and the exciter coils when used) from the stator core.

The nature and objects oi the instant invention will become apparentfrom the following description, appended claims, and accompanying l0drawing wherein:

Figure 1 is an end elevation, partly ln section, of a motor embodyingthe principles of the instant invention and showing the insulation oithe windings from the armature core and the insulal tion of the statorcoils and the exciter coils from the stator core; Figure 2 is anenlarged perspective view of the insulating material;

Figure 3 is a perspective view of one form of 20 the insulating materialas used;

Figure 4 is an enlarged .detail of an armature slot, the windingstherein, and the insulation therebetween; and

Figure 5 is an enlarged detail of the stator slot 5 and the coilstherein and the insulation therebetween.

In one embodiment of this invention, the armature slots and the statorslots of a motor are lined with an insulating material, more fullyhereafter explained, in order to insulate the windings and coils fromthe armature core and the stator core respectively.

In a compound-Wound machine having a starting winding (exciter coil) anda run winding (stator coil), the instant invention also contemplatesinsulating said starting winding from said run Winding as well asinsulating said windings from the stator.

The insulating material above referred to and contemplated by theinstant invention is a laminated material of appropriate dimensions(depending on the place where it is to be used) and having a highvoltage resistance, high strength', resistance to water (waterproof)etc. In the preferred embodiment of the invention, the insu' latingmaterial consists essentially of threecoextensive plies or laminaeadhesively secured together. Paper, bleached or not as desired, andconsisting essentially of half rag and half sulphite fibers, with orwithout a pigment and with or without fillers, modifying ingredients,etc., constitutes the inner ply. Each of the outer plies consistsessentially of a cellulose derivative and specifically celluloseacetate. 'I'hough the outer plies may be free of softeners orplasticizers, Il

(Cl. P11-206) prefer to use cellulose acetate containing a sufilcientquantity of a plasticizer to impart thereto the desired degree ofsoftness, plasticity and ilexibility. Satisfactory results have beensecured when dibutyl phthalate constitutes the plasticizer l andispresent in an amount oi approximately 30%, by weight, based on thecellulose acetate.

For some purposes, it is not necessary to employ the three-ply materialabove described. In many instances, a two-ply material gives the desiredresults. 'Ihis two-ply material consists of a ply of paper (of the .typeabove described) adhesively secured to a ply of cellulose acetate, alsoabove described. In other words, the ply of cellulose acetate is securedto one side onlycf the u Papel.

In producing the insulating material, a web of paper and coextensivesheets or films of cellulose acetate are laminated together, andthereafter the resulting product is cut and slit into pieces oi thedesired dimensions (length and width) The cellulose acetate sheets orlms may be laminated to the paper in any suitable way. For example, anassembly of the two or three plies arranged in the desired relationshipis subjected to heat and pressure, the heat being of a temperaturesumcient to render the cellulose acetate thermoplastic and the pressuresufficient to bring the contiguous surfaces of the materials intointimate relationship. Heated pressure rolls are an i illustrativeapparatus for carrying out this form of laminating.

An alternative procedure for laminating the cellulose acetate sheetingsto the paper contemplates applying, toat least one of the surfaces ofthe materials which are to be in superposed contactual relationship, asolvent which will render the cellulose acetate tacky and adhesive, thensuperimposing the materials, and subjecting them to pressure to eectuniting of the materials. It is, of course, to be understood that inthis form an excess quantity of solvent is to be avoided. In this form,the term solvent is intended to cover a single solvent, a solventmixture, a swelling agent, a swelling agent mixture, etc.

In still another embodiment, the material constituting the plies of theproduct may be laminated together through the medium of a satisfactoryadhesive. lAny suitable adhesive which gives a firm bond, and which doesnot crack or loosen even upon ilexing or bending of the product, may beemployed. As specific illustrative examples of adhesives which havegiven satisfactory results may be mentioned (l) A re'sin (either naturalor synthetic) of thedesired softness;

(2) A resin (either natural or synthetic) and a softener;

(8) Either of the adhesives, defined in (1) and (2), but also containinga cellulose derivative, such as cellulose nitrate, cellulose acetate,cellulose ether, etc.

The aforementioned adhesives are of the thermoplastic nature and resultin a nrm bond which does not crack, or break. or loosen, even when thematerial is flexed or bent.

In some cases, it may be desirable to utilize an adhesive of a lesserviscosity than that of the aforementioned adhesives. The viscosity ofthe adhesive may be controlled by the incorporation therein of thedesired amount of solvent.

In the event the moisture content of the paper is higher than desirable,it may be reduced in any convenient manner.

To show the properties of the insulating material there is hereafter setforth a comparative table showing the properties of (1) 'I'he paper perse;

(2) The two-ply material, i. e. paper having cellulose acetate laminatedto one side thereof; and

(3) The three-ply material, i. e. paper having cellulose acetatelaminated to each side thereof.

panying drawing showing an illustrative embodiment of the invention andwherein like reference numerals designate like parts and wherein thereference numeral I designates a dynamoelectric machine, such as acompound-wound machine, containing an armature core 2 and a stator 3.The armature core is preferably of the laminated type and is providedwith a plurality of spacedslots'l in the outer periphery thereof. Theslots 4 are so formed that the projecting edges 5 of the spaced segments6 of the core 2 constitute lips. An insulated wire is wound into theslots 4 depending on the nature of the windings desired, and saidwindings constitute the armature windings 1.

The coils of the windings 1 are insulated from each other in the usualmanner by having an insulated cover thereon. In order to insulate thewindings I from the core 2, each slot is lined with an insulatingmaterial 8, hereinafter` more fully described. y

The stator 3 is preferably also built up of soft steel laminations andis provided with stator slots 9 on the inner periphery thereof, havinglips 9', and in which slots the stator coils I0 are positioned. The runwinding or stator coils I are formed'of insulated wire whereby they areinsulated from each other. 'I'he stator coils I0 are insulated from thestator 3, in accordance Marita .M35-coated with cellulose acetate 55%relative humidity at 72 F.

Tensile Material Thick- Weght Length Cross Mullen Total pgflr Mois nessvolts products turc Tensile Elonga- Tensile Elongastrength tion strengthtion .Percent lcrcent Pe-rceni .0135 282.6 142 2.2 80 5.8 m5 2,800 1936.1 0151 307. 8 166 3. 3 86 6. 6 234 4, 300 285 6. 4 0168 345. 8 176 3.6 102 0. 8 300 8, 300 494 5. 7

The following are explanations ofthe captions in the above table:

Thickness is in inches.

Weight is in pounds per M square inches.

Tensile strength is in pounds per square inch as determined on theShopper testing machine.

Elongation is the percent of stretch.

Mullen is bursting strength per square inch as determined on a Mullentester.

Total volts is the number of volts the material will stand beforepunoturing.

Volts per mil product is the number of volts the material stands per.001".` A

Moisture is the percentage of moisture in the material.

From the above table, it is apparent that the products contemplated bythis invention have a relatively high voltage resistance, and that theincrease in voltage resistance of the product contemplated by theinstant invention over that of the paper per se is indeed mostsurprising. The insulating material of the instant invention iswaterproof. It is ilexible and possesses an inherent high degree ofresiliency. Thus, the material may be flexed and, due to the inherentre- A siliency thereof, it will seek to return to its nor-a mal positiona property which is highly important as will hereafter appear.

Best results are obtained in motors varying from 115 to 5 horsepower andwherein the temperature does not exceed 200 ii.

In` order to more fully explain the instant invention, reference willnow be made to the. accomwith this invention, by disposing an insulatingmaterial II between the said stator and the said stator coils.

In the form shown, the stator 3 is also provided with a starting windingor exciter coils I2 which are also disposed in the stator slots 9 and injuxtaposition to the stator coils I0 as shown in the drawing. Theexciter coils I2 are also iormed of insulated wire whereby they areinsulated from each other. They are insulated from the stator coils Il)by the insulating material I 3 interposed therebetween. To insulate thenormally exposed surfaces of the exciter coils I2, there is provided theinsulation I4. The insulating material Ii insulates' the stator 3 fromthe exciter coils I2.

Each of the insulating elements 8, II, I3 and I4 are formed in thepreferred embodiment of the invention of a laminated material generallydesighated by the reference numeral i (see Figure 2). This laminatedmaterial I5 is formed of, in the preferred form as shown, three plies,the two outer plies i6 consisting essentially of cellulose acetate, withor without a plasticizer as previously described, and the inner ply Ilformed of paper consisting essentially of approximately half rag andhalf sulphite fibers, with or without a pigment, and which may have beensubjected to a bleaching operation or not as desired. The plies areadhesively secured together in the manner previously described.

To make the insulator elements 3, I I, I3 and it, the laminated materiali5 is slit and cut in any appropriate manner to produce the desired sizeof the strip.

As is clearly shown in Figures 1 and 4, the insulating element 8 ispositioned intermediate the core 2 and the windings 1 in each slot 4. Inother words, the insulating element 8 lines the respective slot. Toinsert the insulating element 8 in position, it is bent in substantiallyU or V- shape and is inserted into'position in the slot 4.

Due to the inherent resiliency of the material I5 from which theinsulating element 8 is made, the legs I8 of the bent element 8 tend toexpand outwardly and assume the normal iiat condition, with theconsequence that the legs I8 exert a pressure on the walls of the slot4, thereby substantially locking the insulation material 8 in position.The insulator also generally conforms to the shape of the slot in whichit is disposed, It is to be noted that the transverse edges of the legsIl are beneath and cooperate with the lips 5.

The ends of the legs I8 in the embodiment immediately before describedare cut edges. If desired, the cut edges may be folded rearwardly ontothe body of the material. Such an embodiment is shown in Figure 3. Thereference numeral I9 therein designates the folds obtained when the cutedges are folded backwardly and lapped over onto the body.

The insulation II employed in the stator slots 8 may be similar in formand construction to the insulation 8 above described.

The insulation I 8 as shown in the drawing, insulates the stator coilsI0 from the exciter coils I2. Though shown as arched, the insulation Ilmay be of any other configuration. It usually takes the form of theexterior surface of the windings IU with which it is in contact.

The insulation I4 is substantially of the same shape and form as theinsulation I8. It ls kept in position by its inherent resiliency andalso the lips 8' of the slot I.

The insulation hereinbefore described is not restricted to any speciilctype of dynamo-electric machine. It may be used in A. C. or D. C.motors. It may be used in motors having rotating or stationary fieldsand it may be used irrespective of the nature and type of amaturewindings, stator coils or exciter coils. It may be used for'electricalinsulation for any purpose whatsoever.

Since it is obvious that various changes and modiiications may be madein the above description without departing from the nature or spiritthereof, this invention is not restricted thereto except as set forth inthe appended claims.

I claim:

1. In a dynamo-electric machine having a core and windings, a resilientlaminated material insulating said core from said windings, saidlaminated material having at least two coextensive pliesthermoplastically secured together, one of said plies being formed ofpaper consisting essentially of `rag and sulphite ilbers and the otherof cellulose acetate.

2. In a dynamo-electric machine having a core and windings, a resilientlaminated material insulating said core from said windings, saidlaminated material having a ply of paper consisting essentially of ragand sulphite bers interposed between two plies formed of celluloseacetate, said plies being coextensive and thermoplastically securedtogether.

3. In a dynamo-electric machine having a slotted core and windings inthe slots, a laminated material disposed intermediate the core and thewindings to insulate said core from said windings, said laminatedmaterial having a ply of paper consisting essentially of rag andsuiphite fibers thermoplastically secured to a coextensive ply formed ofcellulose acetate, said laminated material having a high degree ofinherent resiliency and bent in a substantially U or V shape, the bentmaterial being locked in position and made to generally conform to theshape of the slot by the pressure of l the legs of the bent materialexerted on the walls of said slot.

4. In a dynamo-electric machine having a slotted core and windings inthe slots, a laminated material disposed intermediate the core and thewindings to insulate said core from said windings, said laminatedmaterial having a ply of paper consisting essentially of rag andsulphite bers thermoplastically secured between coextensive plies formedof cellulose acetate, said laminated material having a high degree ofinherent resiliencyand bent in a substantially U or V shape, the bentmaterial being locked in position and made to generally conform to theshape of the slot by the pressure of the legs of the bent` materialexerted on the walls of said slot.

5. An insulating materiaL'suitable 'for insulating slot cells fromwindings therein in dynamoelectric machines, comprising a resilientlaminated material having at least two coextensive pliesthermoplastically secured together. one of said plies being formed otpaper consisting essentially of rag and sulphite nbers and the otherformed of cellulose acetate.

6. An insulating material, suitable for insulating slot cells fromwindings therein in dynamoelectric machines, comprising a resilientlaminated material having a ply ot paper consisting essentially o! ragand sulphite iibers and interposed intermediate and thermoplasticallysecured to two plies o! cellulose acetate.

KARL l. PRINDLI.

